• Journal of the Korea Concrete Institute
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• v.13 no.2
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• pp.146-152
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• 2001

The fractal geometry is a non-Euclidean geometry which discribes the naturally irregular or fragmented shaps, so that it can be applied to fracture behavior of materials to investigate the fracture process. Fractal curves have a characteristic that represents a self-similarity as an invariant based on the fractal dimension. This fractal geometry was applied to the crack growth of cementitious composites in order to correlate the fracture behavior to microstructures of cemposite composites. The purpose of this study was to find relationships between fractal dimensions and fracture energy. Fracture test was carried out in order to investigate the fracture behavior of plain and fiber reinforced cement composites. The load-CMOD curve and fracture energy of the beams were observed under the three point loading system. The crack profiles were obtained by the image processing system. Box counting method was used to determine the fractal dimension, D$_{f}$. It was known that the linear correlation exists between fractal dimension and fracture energy of the cement composites. The implications of the fractal nature for the crack growth behavior on the fracture energy, G$_{f}$ is appearent.ent.

• Proceedings of the Korea Database Society Conference
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• 1999.06a
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• pp.435-444
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• 1999

현재까지 연구되고 있던 정보보호관련분야의 계량화방법을 좀 더 다른 방법으로 접근하여, 정보시스템 환경 하에서 보안 및 관리 운영 평가 지수에 계량화하여 1차 집단과 2차 집단간의 차이를 연구하였다. 정보화 관련항목에 대하여 빈도 분석을 적용함으로서 군별, 항목별 분류를 통한 항목 비례 가중치법을 산출하였다. 또한, 선지정 가중치법을 이용하여, 보호지수와 관리운용지수에 따른 상관관계를 조사하여 안전관리 지수를 계량화하였다.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 1999.03a
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• pp.435-444
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• 1999

현재까지 연구되고 있던 정보보호관련분야의 계량화방법을 좀 더 다른 방법으로 접근하여, 정보시스템 환경 하에서 보안 및 관리 운영 평가 지수에 계량화하여 1차 집단과 2차 집단간의 차이를 연구하였다. 정보화 관련항목에 대하여 빈도 분석을 적용함으로서 군별, 항목별 분류를 통한 항목 비례 가중치법을 산출하였다. 또한, 선지정 가중치법을 이용하여, 보호지수와 관리운용지수에 따른 상관관계를 조사하여 안전관리 지수를 계량화 하였다.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.10a
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• pp.309-310
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• 2001

음파산란층은 전세계 해양에 존재하는 현상으로 동물플랑크톤 또는 소형유영동물의 수직이동과 밀접한 관계가 있다 (Sameoto, 1982: Chou et al.,1999). 이러한 음파산란층의 음파산란강도는 동물플랑크톤의 밀도 및 생물량에 비례하므로 동물플랑크톤을 포함하는 해양생물의 분포 및 생물량 평가를 위한 유용한 기법으로 고려되어 왔다(Smith et al.,1989; lida et al.,1996). 국내에서도 대한해협을 중심으로 음파산란신호를 이용한 동물플랑크톤의 분포를 추정한 바 있다 (Na and Park, 1989). (중략)

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.1183-1184
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• 2010

• Journal of environmental and Sanitary engineering
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• v.11 no.1
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• pp.1-8
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• 1996

In the present study the sesamin and sesamol contents of the sesame extracts prepared from nine provinces in Korea were determined HPLC method. A comparative test was also carried out using the Villavecchia-suarez test, the red colored reaction for the sesamol and sesamol derivatives. The contents of sesamin and sesamol of the sesame oils from each area by the HPLC method were 0.57-0.78% and 0.010-0.023%, respectively, and the paralled results were obtained by the Villavecchia-suarez test and the HPLC method. The average content of the sesamin was $0.68{\pm}0.074%$ by the HPLC method and the average absorbance of the Villavecchia-suarez test was $0.56{\pm}0.034$. The contents of sesamol from sesame oil by the HPLC method and the Villavecchia-suarez test were so low that it was not possible to correlate with the sesamin contents. The contents of sesamol from the sesame oil produced in Kyeong-gi and Jeon-nam provinces were $0.010{\pm}0.002%$ and $0.023{\pm}0.004%$, respectively.

• Industry Promotion Research
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• v.5 no.1
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• pp.1-11
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• 2020

The purpose of this study is to analyze the industrial accidents data with survival model. EDA approach is used to explore the relationship between two variables and among three variables for the past 10 years of industrial accidents data. Survival models are also tried. Survival curve drops more rapidly for the business with fewer employees as time goes by. Industrial accidents occur more often as the total number of industrial accidents gets larger and as the number of employees gets smaller. Agriculture, fishing and forestry have a higher level of industrial accidents than construction while service industry and 'transportation·storage and telecommunication' have a fewer number of industrial accidents than construction. Korea Safety and Health Agency's and Ministry of Employment and Labor's involvement were not effective but Civilian's was. Recurrent event data analysis reveals all most the same result as for non-recurrent data analysis.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.2
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• pp.151-155
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• 1990

A field experiment was conducted to study both the distribution characteristics of shortwave radiation in the soybean canopy and its relationship with dry matter production. The soybean 'Paldalkong' was sown with the space of 45${\times}$10cm at Suwon on May 27. 1988. The extinction coefficient of solar radiation remained constant (0.53) after full canopy was reached. The 31.9% of the incoming solar radiation was transmitted. The reflected radiation from the plant canopy increased lineary with incoming solar radiation (R$^2$=0.9346). As leaf area index become larger than 2.5. the reflected radiation showed more significant linear relationship with the differences in the radiations between incoming and transmitted radiation than incoming solar radiation (R$^2$=0.9558). The mean reflectance during the growing period was 24.7%. A significant linear relationship (R$^2$=0.9930) had been admitted between the accumulated solar radiation intercepted by the canopy and dry matter production of 'Paldalkong' until the 35th day of ripening stage. The conversion efficiency of solar radiation intercepted to dry matter of soybean was 1.45g MJ$\^$-1/.

• Magazine of the Korea Concrete Institute
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• v.8 no.5
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• pp.156-162
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• 1996

The purpose of this study is to find experimentally bond properties of deformed bars in high strength concwtc. Bond properties of deformed bars in high strength concrete are tested i n tensile stress state. Eighty beam-end specimens are used for this experiment. Concrete compressive strength is used as main experimental variable, in addition a few variables affecting bond properties are used : bond length, cover thickness and bar diameter. The principal results obtained from this study are as follows ; - Bond strength is not proportionate to bond length in high strength concrete. The rate of bond strength increase followed by bond length rapidly diminish according to concrete strength increase. The reason is analyzed in FEM analysis that bond stress is not uniformly distributed in high strength concrete and concentrate on loading area. - Bond strength is linearly proportionate to cover thickness without regard to concrete strength. Especially the rate of strength increase is gradually increased by concrete strength.

• Journal of Korean Society of Transportation
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• v.23 no.2
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• pp.151-160
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• 2005

In case of public transit such as bus system, the probability concept is used to evaluate the Level-of-Service of the operations. And each levels could be classified according to the linear probability value. (TCQSM: Transit Capacity and Quality of Service Manual-2nd Edition, TRB, Washington DC., 2003) In this case, the drivers or passengers wouldn't think that the service level isn't equivalent to the linear probability value. Thus the linear probability value doesn't exactly reflect the service level. This study shows the problems of using the linear probability value in classifying the service level through the case of evaluation of bus operation's punctuality, presented in TCQSM. To make up for the problems of such case, two methodologies are presented in this study. The method of determining Level-of-Service criteria using probability density of headway variation's distribution, presented in this paper, adequately reflects passenger's expected waiting time. According to the application result to real bus operation data, it tis better than the method of TCQSM to evaluate the reliability of bus operations. However further research about the relations between utility difference and passenger feeling of service level in necessary to apply the method that uses the utility function. It remains as the limitation of this paper.